FDA approved a new Alzheimer’s drug despite controversy over whether it works

The U.S. Food and Drug Administration has approved a controversial Alzheimer’s treatment, the first that promises to slow the disease’s destruction in the brain, not just improve symptoms.

The drug, aducanumab, is also the first new Alzheimer’s treatment approved since 2003. It doesn’t cure or reverse Alzheimer’s disease, which affects more than 6 million people in the United States and is projected to affect nearly 13 million people by 2050.

The drug’s path to approval hasn’t been smooth. In 2019, aducanumab was nearly scrapped after it appeared unlikely to succeed in two large clinical trials. But after reanalyzing more data that came in later, the drug’s developer, Biogen, which is based in Cambridge, Mass., saw signs that indicated the drug might work after all, and decided to pursue FDA approval (SN: 12/5/19).

Still, today’s decision concerns some doctors and scientists who see the FDA’s move as premature because they aren’t convinced that the drug, also known as Aduhelm, actually works. Approving a drug that’s not effective would set Alzheimer’s research back and offer patients false hope, those experts argue.

“This is a great day for Biogen and its shareholders, but a bleak day for the field of Alzheimer’s research,” says Michael Greicius, a neurologist at Stanford University. Pushing forward on the “illusion of progress,” he says, “will come at a cost to genuine progress in finding an effective treatment for this devastating disease.”

Others disagree that the evidence is slim, and are elated about having a new tool to fight a disease that has eluded an effective treatment for so long. “We have been waiting decades for this,” says neuroscientist Maria Carrillo, chief science officer at the Alzheimer’s Association in Chicago. A drug that delays decline due to Alzheimer’s promises patients and their families time “to sustain independence, to hold onto memories longer, to be with families longer,” she says. “That’s important.”

The drug, which is administered intravenously, is a lab-made antibody that targets small and large clumps of the sticky protein amyloid-beta. Some researchers suspect that in Alzheimer’s, A-beta scrambles connections between nerve cells and damages brain tissue, ultimately causing Alzheimer’s symptoms. But that idea, called the amyloid hypothesis, is still unsettled (SN: 2/25/11).

Brain scans reveal that aducanumab is effective at reducing A-beta in the brain. What’s less clear is whether this reduction comes with consistent improvements in people’s quality of life. That uncertainty led an FDA advisory panel to object strongly to the drug’s approval. In November, that group concluded that the evidence was too weak to show that the drug effectively treated Alzheimer’s (SN: 11/6/20).

Aducanumab comes with potentially serious side effects. Brain scans show that about 40 percent of people who received the highest dose of aducanumab in a clinical trial had swelling or bleeding in the brain. While most of those people had no symptoms, some had headaches, nausea and dizziness.